The field of the invention is drive means for the displacement of slides and the present invention is particularly concerned with the displacement of x-y stages used in microscopes and similar instruments.
It is known in the prior art to support microscope slides in roller bearings or the like, or also to support the microscope slides in glide bearings such as for instance in dovetailed guide means, and to render them displaceable by the use of rack-and-pinion drives. The pinion in these devices engages the rack, which is mounted at the side of the slide or attached to the fixed slide component in the direction of displacement. Ordinarily a knurled knob is mounted on the pinion shaft and is rotated manually, whereby the slide is moved through the intermediary of rack and pinion.
In the so-called x-y stages, two such slides are arranged in one above the other. The first of these slides can be displaced along a first coordinate axis with respect to the instrument frame and the second slide can be displaced in a second coordinate direction in relation to the first slide. The two pinions and knurled knobs are mounted on mutually coaxial shafts.
A very fine stage displacement adjustability is deliberately achieved. The purpose is to have the capibility of moving into all slide directions very accurately, for instance along the optical instrument axis. On the other hand this fine control suffers from the drawback that a large number of revolutions are required to move the stage from one end position into the other. A rapid displacement of the slide or the x-y stage across large distances is impossible. This is so even when to that end the slide is itself grabbed and displaced directly. The force required in this direction is so high that even in this manner the slide can only be displaced slowly.
However, there are many applications for such slides or x-y stages where it is desired to have, in addition to the fine control of the knurled knob and the pinion, the latitude to rapidly displace the stage.